1. Field of the Invention
The invention relates to a quick adjust power adjuster for a seat track of an automotive vehicle seat assembly. More particularly, the invention relates to a quick adjust power adjuster having a split nut for selectively providing either powered or manual fore and aft movement of the seat assembly along a floor of an automotive vehicle.
2. Description of Related Art
Automotive vehicles include seat assemblies for supporting seat occupants within a passenger compartment of the vehicle. Typically, the seat assemblies include a generally horizontal seat cushion spaced above a floor of the vehicle and a generally vertical or upright seat back. The seat back is commonly operatively coupled to the seat cushion by a recliner assembly to allow for selective pivotal adjustment of the seat back relative m the seat cushion between a plurality of reclined seating positions. Many seat assemblies also include a seat track assembly coupled between the seat cushion and the floor to provide fore and aft movement of the seat assembly within the vehicle. Typically, the seat track assembly includes a lower track fixedly secured to the floor of the vehicle and an upper track slidably engaging the lower track. The upper track is fixedly secured to a bottom surface of the seat cushion to allow for sliding movement of the seat assembly along the lower track. It is well known in the vehicle seating art to provide a power seat track assembly driven by an electric motor for moving the upper track, and thus the seat assembly, relative to the lower track. Many such power seat track assemblies include a conventional gearbox or drive assembly operatively coupled in a longitudinal channel between the upper and lower tracks for converting rotational input of the motor into linear movement of the seat assembly. Several such examples are described in U.S. Pat. Nos. 8,226,063; 6,015,998; 6,575,421; 6,260,922; 5,816,555; 5,314,158; and 4,700,202. Typically, a threaded lead screw is fixedly secured to the lower track and the gearbox is operatively coupled between the lead screw and the upper track. The gearbox or drive assembly includes a housing having through holes or bores that are offset 90 degrees to align and retain a worm and a gear or worm wheel. The gear includes a threaded internal bore for threadably engaging the lead screw and a geared outer surface for meshing with the worm. In an arrangement of this kind, the worm is driven by a shaft extending from the motor which in turn causes the gear to rotate. Rotation of the gear causes the gear to move in a longitudinal direction along the fixed lead screw which leads to the desired movement of the upper track relative to the lower track.
However, the motor and drive assembly only provides powered fore and aft movement of the upper track relative to the lower track, and hence, the sliding fore and aft adjustment of the seat assembly. It is often desirable to quickly and manually move the seat assembly from a passenger fore/aft adjusted position to a full forward easy entry position wherein the upper track is moved forward along the lower track to a forward most position therebetween to allow easy access and entry into the vehicle behind the seat assembly.